Saving variables? [Unity IOS Dev]

Hello,
My name is Scott, I am quite new to unity development.
I have very little experience in memory management and was wondering what is the best way is to save variables so that when my app is closed and re-opened, the variables (Coins(int), Level unlocks(bool), etc.) will be exactly the same when the application was closed.

I have had a quick look online and noticed Serializable.
Or PlayerPrefs?
I wondered if this is the correct way to go about saving variables or if they is a better/easier way?

If you know anything please link me to some documentation.
Thank you very much or your time!

Serializing things is probably the “better” way when storing values such as coins etc because PlayerPrefs can be easilly edited. Other way to consider is using PHP and a MySQL database to save it online.
(I have never used serialization to save before so I cannot help there.)

Great, Thank you very much for your response! Will look into it all, thanks!

Find the basics here

Depending on how important your save data is, a backend service can serve your needs pretty well. There are several free ones for indie developers or just free for all with some limits in place (such as number of api calls a month)

I have used

Playfab
App42
Heroic Labs
GameSpark